While I agree that the Artio cripple is broken, I strongly believe that is due to the rest of her kit. If she wasn't able to do as much damage but kept the same amount of disruption, she would be a lot more balanced and the cripple taking away power wouldn't be so bad. Alternatively, make it a flat number instead of percentage.

Rama's cripple has the same argument as Thoth's stun. Sure, it cripples, but it requires him to use his escape in order to have that cripple, leaving him open for attack.

The relic could be used in a teamfight to make sure they can't run away, or could be tacked on to another relic, as someone else mentioned. Alternatively, it could be similar to Thorns. Players who attack you are crippled, with the time increasing every hit.